This circuit, with 1 A output, was found in a 1975 documentation. The transistors admit equivalents and the transformer has windings according to the voltages being worked.
This circuit was found in an Electronic Design from 1967. The circuit uses two triacs being T2...
Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz...
This shield from the 60's uses a germanium transistor of the time and a common type of relay of...